JP6484295B2 - Prepreg, manufacturing method thereof, and manufacturing method of composite material - Google Patents

Description

  The present invention relates to a prepreg composed of a sheet composed of reinforcing fibers and a thermoplastic resin impregnated therein, a method for producing the same, and a method for producing a composite material excellent in high-speed impact resistance obtained using the prepreg.

  In recent years, reinforcing fiber composite materials obtained by combining reinforcing fiber materials such as carbon fibers, glass fibers, and aramid fibers and various matrix resins have been widely used in various fields and applications. And in fields and applications such as aerospace and space, where general mechanical properties and heat resistance are required, and general industrial fields, heat of unsaturated polyester resin, epoxy resin, polyimide resin, etc. has been used as matrix resin. A curable resin is used.

  However, these matrix resins have the disadvantage of being brittle and inferior in impact resistance. Therefore, especially in the aerospace field, a thermoplastic resin that has excellent impact resistance when laminated with a prepreg to form a composite material, is easy to store and manage the prepreg, has a short molding time, and may reduce molding costs. However, it has been adopted as a matrix resin (see Patent Document 1).

  When reinforced fiber composite materials are used in aircraft applications, bird strikes that cause objects such as birds to collide at high speed and destroy aircraft components become a problem. That is, the composite material produced by laminating the above-described prepreg cannot withstand the impact generated at the time of high-speed collision, and there is a problem that peeling failure between layers such as a reinforcing fiber resin layer and an interlayer resin layer is likely to occur. is there. Therefore, in aircraft applications, high speed impact resistance is required for safety.

  The research group to which the present inventor belongs has selected a thermoplastic resin powder from alcohols, ketones, and halogenated carbons in the production of a prepreg by impregnating a sheet-like reinforcing fiber material with a thermoplastic resin. A prepreg excellent in uniformity and surface smoothness is produced by adopting specific processing conditions using a seed or two or more organic solvents or a suspension dispersed in a mixed solvent of such an organic solvent and water. A method was proposed (see Patent Documents 2 to 4). However, in the proposed method, although the performance of the obtained prepreg is excellent, there is a problem that the above-described high-speed impact resistance is not necessarily high.

Japanese Patent Publication No. 4-12894 JP 2005-238596 A Japanese Patent Laid-Open No. 2005-239843 JP 2008-44165 A

  An object of the present invention is a prepreg that solves the above-described problems of the prior art, and a prepreg that suppresses delamination behavior between layers at the time of high-speed collision with respect to a composite material that is produced by laminating the prepreg, a manufacturing method thereof, and An object of the present invention is to provide a method for producing a composite material using the prepreg.

The present inventor, according to a predetermined manufacturing method, a reinforcing fiber resin layer having an intermediate resin layer made of a thermoplastic resin between a plurality of reinforcing fiber sheets impregnated with a thermoplastic resin, and at least one surface of the reinforcing fiber resin layer The ratio of the basis weight [A] of the thermoplastic resin to the basis weight [B] of the surface resin layer is 0.15 <[B] / [A] <0. .50
Was obtained. The composite material produced using this prepreg has an interlayer resin layer formed between the reinforced fiber resin layers of the composite material, and can suppress the peeling behavior between layers such as the reinforced fiber resin layer and the interlayer resin layer at the time of high-speed collision. The present inventors have found that this can be done and have completed the present invention.

  The present invention for achieving the above object is as follows.

[1] A reinforcing fiber resin layer having an intermediate resin layer made of a thermoplastic resin between a plurality of reinforcing fiber sheets impregnated with a thermoplastic resin, and a surface resin layer formed on at least one surface of the reinforcing fiber resin layer; The ratio of the basis weight [A] of the thermoplastic resin contained in the reinforcing fiber resin layer to the basis weight [B] of the surface resin layer is 0.15 <[B] / [A ] <0.50
The prepreg that is.

  [2] The prepreg according to [1], wherein the thermoplastic resin is a crystalline or amorphous thermoplastic resin having a melting point or glass transition temperature of 150 ° C. or higher.

  [3] The thermoplastic resin is polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, polyamide The prepreg according to [1] or [2], which is one or two or more resins selected from the group consisting of imides.

[4] A reinforcing fiber resin layer having an intermediate resin layer made of a thermoplastic resin between a plurality of reinforcing fiber sheets impregnated with a thermoplastic resin, and a surface resin layer formed on at least one surface of the reinforcing fiber resin layer; A prepreg manufacturing method comprising:
In a suspension in which a thermoplastic resin powder is dispersed in a liquid, a plurality of reinforcing fiber sheets, the concentration (mass%) of the thermoplastic resin powder contained in the suspension and the immersion time of the reinforcing fiber sheet are represented by the following formula (1)
10 ≦ Concentration (mass%) of thermoplastic resin powder × Immersion time (seconds) ≦ 250 (1)
A deposition step of obtaining a deposited sheet by depositing the thermoplastic resin powder on the upper surface of a plurality of reinforcing fiber sheets,
A stacking step of removing the deposited sheet from the suspension and stacking these sheets to obtain a stacked sheet;
A thermocompression bonding step of integrating the stacked sheets by heat-pressing the stacked sheets;
The manufacturing method of the prepreg which has.

[5] A reinforcing fiber resin layer having an intermediate resin layer made of a thermoplastic resin between a plurality of reinforcing fiber sheets impregnated with a thermoplastic resin, and a surface resin layer formed on at least one surface of the reinforcing fiber resin layer; A prepreg manufacturing method comprising:
In a suspension in which a thermoplastic resin powder is dispersed in a liquid, a plurality of reinforcing fiber sheets, the concentration (mass%) of the thermoplastic resin powder contained in the suspension and the immersion time of the reinforcing fiber sheet are represented by the following formula (1)
10 ≦ Concentration (mass%) of thermoplastic resin powder × Immersion time (seconds) ≦ 250 (1)
A deposition step of obtaining a deposited sheet by depositing the thermoplastic resin powder on the upper surface of a plurality of reinforcing fiber sheets,
A stacking step of removing the deposited sheet from the suspension and stacking these sheets to obtain a stacked sheet;
A layering step of stacking resin sheets made of the same material on the deposition surface of the thermoplastic resin powder of the stacking sheet to obtain a multilayer sheet;
A thermocompression bonding step in which the stacked sheets are integrated by heat-pressing the multilayer sheet;
The manufacturing method of the prepreg which has.

  [6] A method for producing a composite material formed by laminating a plurality of the prepregs according to any one of [1] to [3].

  The prepreg of the present invention is a prepreg having an intermediate resin layer containing a lot of thermoplastic resin between a plurality of reinforcing fiber sheets impregnated with a thermoplastic resin. A composite material in which an interlayer resin layer having an appropriate thickness is formed between the reinforcing fiber resin layers of the composite material is obtained. This composite material can suppress peeling behavior between layers such as a reinforcing fiber resin layer and an interlayer resin layer at the time of high-speed collision.

It is the schematic which shows an example (manufacturing process of a stacked sheet) of the manufacturing process of this invention prepreg. FIG. 2 is a schematic cross-sectional view showing an example (stacked sheet) of the prepreg of the present invention. FIG. 3 is a schematic view showing another example of the production process of the prepreg of the present invention (production process of a multilayer sheet). FIG. 4 is a schematic cross-sectional view of a situation where a thermoplastic resin sheet is overlaid on a stacked sheet in the manufacturing process of another example of the prepreg of the present invention. FIG. 5 is a schematic cross-sectional view showing another example (multilayer sheet) of the prepreg of the present invention.

  Details of the present invention will be described below.

The prepreg of the present invention is a prepreg composed of reinforcing fibers and a thermoplastic resin, and an intermediate resin layer composed of a thermoplastic resin is provided between a plurality of reinforcing fiber sheets (resin-impregnated fiber layers) impregnated with the thermoplastic resin. A reinforcing fiber resin layer having a surface resin layer is formed on at least one surface of the reinforcing fiber resin layer. In the present invention, the reinforcing fiber resin layer preferably has a thickness of 100 to 300 μm, and the surface resin layer preferably has a thickness of 15 to 40 μm. Furthermore, in the prepreg of the present invention, the ratio of the basis weight [A] of the thermoplastic resin contained in the reinforcing fiber resin layer and the basis weight [B] of the surface resin layer is 0.15 <[B] / [A] <0. .50
It is. In this invention, it is preferable that content of the thermoplastic resin in a prepreg is 10-70 mass%, and 20-50 mass% is more preferable.

  In the present invention, the surface resin layer only needs to be formed on at least one surface of the prepreg, and may be formed on both surfaces of the prepreg. In the present invention, when the surface resin layers are formed on both surfaces of the prepreg, the thickness of the surface resin layer and the basis weight of the surface resin layer [B] refer to the combined thickness and basis weight of the surface resin layers on both sides of the prepreg. . When the surface resin layer is formed only on one surface of the prepreg, it is easy to reduce variations in the thickness of the surface resin layer and the basis weight [B].

  By laminating and heat-pressing this prepreg, a composite material in which an interlayer resin layer is formed between the reinforcing fiber resin layers of the composite material is obtained. The thickness of the interlayer resin layer can be appropriately adjusted according to the basis weight [A] of the thermoplastic resin contained in the reinforcing fiber resin layer, and is preferably 10 to 20 μm. This composite material can suppress peeling behavior between layers such as a reinforcing fiber resin layer and an interlayer resin layer at the time of high-speed collision.

The prepreg of the present invention is, for example, a suspension in which a thermoplastic resin powder is dispersed in a liquid, a plurality of reinforcing fiber sheets, the concentration (mass%) of the thermoplastic resin powder contained in the suspension, and the immersion time of the reinforcing fiber sheet. Is the following formula (1)
10 ≦ Concentration (mass%) of thermoplastic resin powder × Immersion time (seconds) ≦ 250 (1)
A deposition step of obtaining a deposited sheet by depositing the thermoplastic resin powder on the upper surface of a plurality of reinforcing fiber sheets,
A stacking step of removing the deposited sheet from the suspension and stacking these sheets to obtain a stacked sheet;
A thermocompression bonding step of integrating the stacked sheets by heat-pressing the stacked sheets;
It can obtain by the manufacturing method of the prepreg which has.

  As the liquid for dispersing the thermoplastic resin powder, one or two or more solvents or mixed solvents selected from water, alcohols, ketones, and halogenated carbons can be used. The average particle size of the thermoplastic resin powder is preferably 5 to 50 μm.

  In the thermocompression bonding step, it is preferable to heat-press the stacked sheets at a melting point of the thermoplastic resin powder +50 to 200 ° C. and 500 to 1000 kPa.

  An example of the prepreg manufacturing method of the present invention will be described with reference to FIG.

  In FIG. 1, 2 is a suspension, 4a and 4b are sheets made of reinforcing fibers, 6a and 6b are both introduction rollers for reinforcing fiber sheets, 8 is a take-up roller for stacked sheets, 10a to 10d are guide rollers, and 12 is stacked. It is a heavy sheet.

  The reinforcing fiber sheets 4a and 4b are introduced and immersed in the suspension 2 through the introduction rollers 6a and 6b, respectively. As a result, the thermoplastic resin powder 14 floating in the suspension 2 is deposited on the upper surfaces of the sheets 6a and 6b by gravity settling (the direction of gravity is indicated by X).

In the present invention, in the deposition step, the concentration [T] (mass%) of the thermoplastic resin powder contained in the suspension and the immersion time [M] (second) of the reinforcing fiber sheet are expressed by the following formula (1).
10 ≦ [T] × [M] ≦ 250 (1)
The reinforcing fiber sheet is immersed under the conditions satisfying

  By adjusting the concentration and immersion time of the thermoplastic resin powder to such a range, an appropriate amount of thermoplastic resin powder settles on the reinforcing fiber sheet, and the fiber layer resin basis weight [A] and the surface layer resin basis weight [B] of the prepreg. Can be in the desired range of 0.15 <[B] / [A] <0.50.

  When [T] × [M] is less than 10, the amount of thermoplastic resin powder deposited on the reinforcing fiber sheet is small, and [B] / [A] is less than 0.15. On the other hand, when [T] × [M] is more than 250, the amount of the thermoplastic resin powder deposited on the reinforcing fiber sheet is too large, and [B] / [A] is larger than 0.50, so that the prepreg is easy to handle. Decreases. [T] × [M] is preferably 50 to 100, and more preferably 50 to 90.

  The concentration [T] (mass%) of the thermoplastic resin in the suspension is determined as [thermoplastic resin weight / (liquid weight + thermoplastic resin weight) × 100], and preferably 1 to 15 mass%. The mass% is more preferable.

  The sheets 4a and 4b on which the thermoplastic resin powder 14 is deposited on the upper surface in the deposition step are taken out from the suspension 2 and stacked in the stacking step, and are stacked as a single stacked sheet 12 through the take-up roller 8 in the next step. Derived into the thermocompression bonding process.

  In addition, in the stacked sheet 12 of FIG. 1, although the example using 2 sheets 4a and 4b which consist of a reinforced fiber was shown, 3 sheets, 4 sheets, or more sheets were used by increasing an introduction roller. It is also possible to produce a single stacked sheet. Further, as long as the guide rollers 10a to 10d are arranged so that the respective sheets can be sufficiently immersed in the suspension 2, the number and arrangement position thereof are not limited.

  On the other hand, when one sheet made of reinforcing fibers is used, that is, when it is not a stacked sheet, the obtained prepreg product is warped, which is not preferable.

  The stacked sheet 12 obtained through the deposition process and the stacking process described above is the next thermocompression bonding process, that is, the stacked sheet 12 taken out from the suspension 2, preferably the melting point of the thermoplastic resin powder +50 to 200. The thermoplastic resin is impregnated with high uniformity in the reinforcing fiber sheet by passing through a thermocompression bonding step in which the stacked sheets are integrated by applying heat and pressure at 500 ° C. and 1000 kPa.

  On the other hand, when the thermoplastic resin sheet is stacked on the reinforcing fiber sheet and melted and impregnated, (1) the uniformity of the impregnated resin is low and (2) it is difficult to vent the air during the impregnation. Absent.

  When the thermoplastic resin is placed on the reinforcing fiber sheet in a dry manner and melted and impregnated, the impregnation property into the reinforcing fiber sheet is extremely bad, which is not preferable.

  As the sheets 4a and 4b made of reinforcing fibers, those in which fiber base materials are aligned in one direction in a sheet shape, those obtained by laminating them, for example, and fiber materials formed into a fabric such as a woven fabric, a knitted fabric, or a nonwoven fabric In addition, all strands such as braids are included, but it is preferable that the strand-like fiber material is aligned in a sheet shape in one direction.

  Examples of the reinforcing fibers constituting the sheets 4a and 4b include carbon fibers, glass fibers, aramid fibers, silicon carbide fibers, polyester fibers, ceramic fibers, alumina fibers, boron fibers, metal fibers, mineral fibers, rock fibers, and slug fibers. Etc. can be used. Among these reinforcing fibers, carbon fibers, glass fibers, and aramid fibers are preferable, carbon fibers that provide a lightweight and high-strength fiber-reinforced composite material with favorable specific strength and specific elastic modulus are more preferable, and are excellent in tensile strength. Acrylonitrile (PAN) based carbon fibers are particularly preferred.

  The thermoplastic resin used in the present invention is not particularly limited, but a crystalline or amorphous thermoplastic resin having a melting point or glass transition temperature of 150 ° C. or higher is preferable. Specific examples of preferred resins include polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic or aliphatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplasticity Examples thereof include polyimide and polyamideimide. These resins may be used alone or in combination of two or more. Moreover, these copolymers can also be used. For aircraft prepregs, polyetherimide (PEI) or polyimide (PI) is particularly preferred.

  In the present invention, the resin powder has a particle diameter of 50 μm or less in consideration of good deposition on the reinforcing fiber material (a state in which the resin powder is held between the fibers or on the fiber surface), from the viewpoint of handleability. It is good that it is not less than 1 μm, and an average particle size in the range of 5 to 20 μm is preferable. When dispersed in the liquid described below, the thermoplastic resin powder in the above particle size range has a stable dispersibility (dispersibility of the resin powder in the suspension). It has the feature that powder can be deposited stably.

In the present invention, the average particle size refers to the value of the cumulative 50 volume% particle size (D ₅₀ ) of the particle size distribution measured using the laser diffraction / scattering method.

  The liquid for dispersing the thermoplastic resin used in the present invention is preferably one or two or more solvents or mixed solvents selected from water, alcohols, ketones and halogenated hydrocarbons. Examples of alcohols include methanol, ethanol, isopropyl alcohol, and methyl cellosolve. Examples of ketones include acetone and methyl ethyl ketone. Examples of halogenated hydrocarbons include methylene chloride and dichloroethane. Of these, ethanol, isopropyl alcohol, acetone, a mixed solvent thereof with water, or water is preferable. Such a liquid also has an effect of appropriately opening the fiber material when the sheet-like reinforcing fiber material is immersed, and is therefore effective in uniformly depositing the resin powder in the suspension on the fiber material.

  The combination of the thermoplastic resin and the liquid (solvent) to disperse it should not be such that the resin is soluble in the solvent and the resin must swell or not dissolve in the solvent. .

  The concentration of the thermoplastic resin in the suspension [thermoplastic resin weight / (liquid weight + thermoplastic resin weight) × 100] is preferably 1 to 15% by mass, and more preferably 1 to 10% by mass.

  The temperature of the suspension when the sheet-like reinforcing fiber material is immersed is not particularly limited as long as the dispersion state of the resin is kept good, and varies depending on the type and concentration of the thermoplastic resin and liquid used. Is 5 to 50 ° C, preferably 5 to 30 ° C, more preferably 15 to 30 ° C.

  Under the above conditions, the sheet-like reinforcing fiber usually deposits 10 to 70% by mass (based on the total amount of the reinforcing fiber and the thermoplastic resin) of thermoplastic resin powder. 20-50 mass% is more preferable above.

  In FIG. 1, a stacked sheet 12 made of reinforcing fibers led out from the suspension 2 through the take-up roller 8 is usually introduced into a dryer (not shown) and dried by removing the liquid. Drying conditions and methods are not particularly limited, but are usually dried at a temperature at which the thermoplastic resin does not decompose or react. Generally, it is dried at 80 to 200 ° C. for 1 to 20 minutes.

  Next, the stacked stack sheet 12 is heated to such an extent that the thermoplastic resin powder 14 deposited on the surfaces of the sheets 4a and 4b melts, preferably at the melting point of the thermoplastic resin powder +50 to 200 ° C. and 500 to 1000 kPa. The stacked sheets 12 are integrated by being pressurized.

  When the surface resin layer at the time of preparing the prepreg is less than 15 μm, the resin layer between the layers becomes less than 10 μm when the composite material is formed, and a sufficient resin layer thickness may not be obtained for suppressing the peeling behavior. When the surface resin layer at the time of prepreg production exceeds 40 μm, the prepreg tends to warp due to the difference in thermal shrinkage between the resin and the fiber at the time of prepreg production, and the handleability tends to deteriorate.

  If the ratio [B] / [A] between the basis weight [B] of the surface resin layer formed on the prepreg surface and the basis weight [A] of the thermoplastic resin contained in the reinforced fiber resin layer is less than 0.15, the reinforcement Since the basis weight [B] of the surface resin layer is smaller than the resin basis weight [A] of the fiber resin layer, an interlayer resin layer having a sufficient buffering effect cannot be formed in the composite material obtained using this prepreg. When [B] / [A] exceeds 0.5, the basis weight [A] of the reinforcing fiber resin layer is smaller than the basis weight [B] of the surface resin layer, and the reinforcing effect of the reinforcing fiber resin layer is insufficient. For this reason, the composite material obtained using this prepreg is warped, resulting in poor handling.

  FIG. 2 is a schematic cross-sectional view showing an example of a stacked sheet in which reinforcing fibers and a thermoplastic resin are integrated, and a surface resin layer having a sufficient thickness is formed.

  As shown in FIG. 2, in the stacked sheet 22, the sheets 4a and 4b (see FIG. 1) made of the reinforcing fibers 24 are impregnated with a thermoplastic resin 26 to form resin-impregnated fiber layers 28a and 28b, respectively. An intermediate resin layer 30a is formed between the resin-impregnated fiber layers 28a and 28b, a surface resin layer 30b is formed near the surface of the stacked sheet 22, and the resin-impregnated fiber layer 28a is formed as a layer other than the surface resin layer 30b. , 28b and the intermediate resin layer 30a are formed.

  The stacked sheet 22 shown in FIG. 2 is used as the prepreg of the present invention. After a plurality of the prepregs are laminated, they are heat-pressed using an autoclave or the like to obtain the composite material of the present invention in which an interlayer resin layer is formed between the reinforced fiber resin layers of the composite material. Under the present circumstances, it is preferable to heat-press at the pressure of 500-2000 kPa, melting | fusing point of the said thermoplastic resin powder + 50-200 degreeC. The thickness of the interlayer resin layer between the reinforcing fiber resin layers of the composite material is preferably 10 to 20 μm.

The prepreg of the present invention described above,
That is, a reinforcing fiber resin layer having an intermediate resin layer made of a thermoplastic resin between a plurality of reinforcing fiber sheets impregnated with a thermoplastic resin (resin-impregnated fiber layer);
A surface resin layer formed on one surface of the reinforcing fiber resin layer;
The ratio of the basis weight [A] of the thermoplastic resin contained in the reinforcing fiber resin layer to the basis weight [B] of the surface resin layer is 0.15 <[B] / [A ] <0.50
The prepreg as described above can be easily obtained by the prepreg manufacturing method having the above-described deposition step, stacking step, and thermocompression bonding step.

The basis weight of the reinforcing fiber is preferably 150 d (g / m ² ) or less [d is the density (g / cm ³ ) of the reinforcing fiber], more preferably 30 to 80 d (g / m ² ).

When the reinforcing fiber is a carbon fiber, the density d of the carbon fiber is 1.8 (g / cm ³ ), and thus the basis weight 150d (g / m ² ) of the reinforcing fiber is 225 (g / m ² ). 80 d (g / m ² ) becomes 144 (g / m ² ).

When the basis weight of the reinforcing fiber of the sheet exceeds 80 d (g / m ² ), the stacked sheet may not have a sufficiently thick surface resin layer. Therefore, the above-described prepreg of the present invention may not be easily obtained. In this case, the above-described prepreg of the present invention can be easily obtained by adding a layering step of laminating a thermoplastic resin film on the surface of the laminated sheet to the above-described deposition step, stacking step, and thermocompression bonding step.

That is, even when the basis weight of the reinforcing fiber of the sheet exceeds 80 d (g / m ² ), the thermoplastic resin sheet is stacked, heated, and pressed on the surface of the stacked sheet by the manufacturing method in which the multi-layer process is added. The prepreg of the present invention for producing a composite material having excellent high-speed impact resistance, comprising a multilayer sheet in which a stack sheet and a thermoplastic resin sheet are integrated, can be easily obtained. This multilayering process may be performed before the thermocompression bonding process or may be performed after the thermocompression bonding process. It is more preferable to perform the multi-layer process before the thermocompression bonding process.

  FIG. 3 is a schematic view showing an example of the production process of the multilayer sheet in the production process of the prepreg of the present invention.

  In FIG. 3, reference numeral 42 denotes a stacking sheet that travels in the direction of the arrow Y. The thermoplastic resin powder deposition surface of the stacked sheet 42 is overlaid with a thermoplastic resin sheet 56 made of the same material as the thermoplastic resin powder supplied from a sheet roll 68. This laminated sheet is heated and pressed by calendar rollers 66a and 66b through a release paper and integrated, and the prepreg (multilayer sheet) of the present invention having the surface resin layer 64 and the reinforced fiber resin layer 52 shown in FIG. ) 62 is manufactured.

  An example of the process of layering the stacked sheet 42 and the thermoplastic resin sheet 56 is shown in FIG. 4 as a schematic cross-sectional view.

  As shown in FIG. 4, in the stacked sheet 42, sheets 4a and 4b (see FIG. 1) made of the reinforcing fibers 44 are impregnated with a thermoplastic resin 46 to form resin-impregnated fiber layers 48a and 48b, respectively. An intermediate resin layer 50a is formed between the resin-impregnated fiber layers 48a and 48b, a surface resin layer 50b is formed near the surface of the stacked sheet 42, and the resin-impregnated fiber layer 48a is formed as a layer other than the surface resin layer 50b. , 48b and the intermediate resin layer 50a are formed.

  As described above, the surface resin layer having a sufficient thickness is not formed on the stacked sheets 42. Therefore, as shown in FIG. 3, the thermoplastic resin sheet 56 is stacked on the surface 54 of the stacked sheet 42, heated, and pressed, and the thermoplastic resin sheet 56 is thermocompression-bonded and integrated with the surface 54 of the stacked sheet 42. The Thereby, as shown in FIG. 5, the multilayer sheet 62 in which the surface resin layer 64 having a sufficient thickness is formed is obtained.

  Similar to the stacked sheet 22 shown in FIG. 2, the multilayer sheet 62 shown in FIG. 4 is also used as the prepreg of the present invention. Similarly to the prepreg of the stacked sheet 22, the prepreg of the multi-layer sheet 62 is preferably laminated after being laminated, and preferably using an autoclave or the like, a pressure of 500 to 2000 kPa, a melting point of the thermoplastic resin powder +50 to 200 ° C. The composite material of the present invention in which an interlayer resin layer of preferably 10 to 20 μm is formed between the reinforcing fiber resin layers of the composite material is obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to an Example. The particle diameter measuring method and the resin layer thickness measuring method used in the examples and comparative examples are as follows.

[Average particle size]
The average particle size was measured by using a particle size analyzer microtrack of a laser diffraction / scattering type particle size analyzer manufactured by Nikkiso Co., Ltd., particle size distribution [cumulative 10 volume% particle diameter (D ₁₀ ), accumulated 50 volume% particle diameter (D ₅₀ ), measurements were performed cumulative 90 volume% particle size (D _90)], a cumulative 50% by volume particle diameter of (D ₅₀₎ was defined as the average particle diameter.

[Thickness of prepreg surface resin layer]
The thickness of the prepreg surface resin layer was measured by cross-sectional observation using a confocal microscope.

[Thickness of interlayer resin layer during lamination]
The thickness of the interlayer resin layer during lamination was measured by cross-sectional observation using a confocal microscope.

[Measurement method of damaged area]
The obtained carbon fiber reinforced composite material was cut into a size of width 101.6 mm × length 152.4 mm to obtain a test piece. Using the obtained test piece, the damaged area after impact of 30.5 kJ is measured by ultrasonic flaw detection. Damage area may have become a 4.5 cm ² or less, desirably becomes 4.0 cm ² or less.

[Example 1]
Polyetherimide resin (manufactured by Subic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a 5.5 mass% suspension in the suspension bath. Carbon fiber A (Tenax IMS 60, 24,000 pieces manufactured by Toho Tenax Co., Ltd.) was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 190 g / m ² .

  Then, two sheets were introduced into the suspension and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bathtub as one stacked sheet. The resulting stacked sheet was dried at 150 ° C. for 5 minutes. The amount of resin deposited was 10.4% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 168 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminated body of a laminated structure [+ 45/0 / −45 / 90] _4S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 16 μm. The damage area of the carbon fiber reinforced composite material thus obtained was small as shown in Table 1.

[Example 2]
Polyetherimide resin (manufactured by Savic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a 4.5 mass% suspension in the suspension bath. Carbon fiber A (Tenax IMS60, Toho Tenax Co., Ltd., 24,000) made of carbon fiber A was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of carbon fiber was 150 g / m ² .

  Then, two sheets were introduced into the suspension and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bathtub as one stacked sheet. The obtained stacked sheet was dried at 150 ° C. for 2 minutes. The amount of deposited resin was 6.0% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 123 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminated body of a laminated structure [+ 45/0 / −45 / 90] _4S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 11 μm. The damage area of the carbon fiber reinforced composite material thus obtained was small as shown in Table 1.

Example 3
Polyether sulfone resin (manufactured by Sumitomo Chemical Co., Ltd., trade name SUMIKAEXCEL) powder (particle size distribution: cumulative 50% by volume, 15 μm particle size) was dispersed in ethanol to prepare a 4.5% by mass suspension in the suspension bath. Carbon fiber A (Tenax IMS 60, 24,000 pieces manufactured by Toho Tenax Co., Ltd.) was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 145 g / m ² .

  Then, two sheets were introduced into the suspension and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bathtub as one stacked sheet. The obtained stacked sheet was dried at 150 ° C. for 2 minutes. The amount of deposited resin was 8.0% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 122 μm. The prepreg thus obtained was laminated and subjected to autoclave molding at 340 ° C. (glass transition temperature of polyethersulfone resin + 120 ° C.) and 1000 kPa to obtain a laminate having a laminated structure [+ 45/0 / −45 / 90] _4S. Obtained. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 10 μm. The damage area of the carbon fiber reinforced composite material thus obtained was small as shown in Table 1.

Example 4
Polyetherimide resin (manufactured by Savic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a suspension having a concentration of 5 mass% in a suspension bath. Carbon fiber A (Tenax IMS60, Toho Tenax Co., Ltd., 24,000) made of carbon fiber A was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of carbon fiber was 198 g / m ² .

  Then, two sheets were introduced into the suspension and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bathtub as one stacked sheet. The obtained stacked sheet was dried at 150 ° C. for 2 minutes. The amount of resin deposited was 5.5% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 163 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminate having a laminated structure [+ 45/0 / −45 / 90] _3S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 11 μm. The damage area of the carbon fiber reinforced composite material thus obtained was small as shown in Table 1.

[ Reference Example 1 ]
Polyetherimide resin (manufactured by Savic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a suspension having a concentration of 6.5 mass% in a suspension bath. Carbon fiber A (Toho Tenax Co., Ltd. Tenax IMS60, 24,000) was aligned in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 196 g / m2.

  Then, two sheets were introduced into the suspension and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bathtub as one stacked sheet. The obtained stacked sheet was dried at 150 ° C. for 2 minutes. The amount of deposited resin was 8.0% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 199 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminate having a laminated structure [+ 45/0 / −45 / 90] _3S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 20 μm. The damage area of the carbon fiber reinforced composite material thus obtained was small as shown in Table 1.

Example 6
Polyetherimide resin (manufactured by Subic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a 3.5% concentration suspension in a suspension bath. Carbon fiber A (Tenax IMS 60, 24,000 pieces manufactured by Toho Tenax Co., Ltd.) was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 145 g / m ² .

  Then, two sheets were introduced into the suspension and immersed for 10 seconds, and then the two sheets were stacked and led out from the suspension bath as one stacked sheet. The resulting stacked sheet was dried at 150 ° C. for 5 minutes. The amount of resin deposited was 1.0% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 116 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminated body of a laminated structure [+ 45/0 / −45 / 90] _4S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 4 μm, which was smaller than that of Example 1. However, the damage area of the obtained carbon fiber reinforced composite material was small as shown in Table 1. It was.

Example 7
Polyetherimide resin (manufactured by Subic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a 5.5 mass% suspension in the suspension bath. Carbon fiber A (Tenax IMS 60, 24,000 pieces manufactured by Toho Tenax Co., Ltd.) was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 190 g / m ² .

  Then, two sheets were introduced into the suspension bathtub and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bathtub as one stacked sheet. The resulting stacked sheet was dried at 150 ° C. for 5 minutes. The amount of deposited resin was 8.0% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 250 ° C. (glass transition temperature of polyetherimide resin + 50 ° C.), and the resin was melted and impregnated.

  In this prepreg, the impregnation of the resin into the reinforcing fiber sheet was less than in Example 1, and the handleability was slightly reduced because the thickness of the surface resin layer of the prepreg was increased to 30 μm, but the resulting composite material was damaged. As shown in Table 1, the area was small.

Example 8
Polyetherimide resin (manufactured by Subic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a 5.5 mass% suspension in the suspension bath. Carbon fiber A (Tenax IMS 60, 24,000 pieces manufactured by Toho Tenax Co., Ltd.) was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 190 g / m ² .

Then, two sheets were introduced into the suspension and immersed for 15 seconds, and then the two sheets were stacked and led out from the suspension bath as one laminated sheet. Further, a film made of polyetherimide resin (manufactured by Savic) (weight per unit area: 10 g / m ² ) was laminated on the upper surface of the laminated sheet to obtain one multilayer sheet. The resulting stacked sheet was dried at 150 ° C. for 5 minutes. The amount of resin powder deposited was 10.4% by mass (the amount of resin in the laminated sheet excluding the resin amount of the film). Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 167 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminated body of a laminated structure [+ 45/0 / −45 / 90] _4S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was 16 μm. The damage area of the carbon fiber reinforced composite material thus obtained was small as shown in Table 1.

[Comparative Example 1]
Polyetherimide resin (manufactured by Savic) powder (particle size distribution: cumulative 50 volume% particle diameter 15 μm) was dispersed in ethanol to prepare a 3.5 mass% suspension in a suspension bath. Carbon fiber A (Tenax IMS 60, 24,000 pieces manufactured by Toho Tenax Co., Ltd.) was drawn in parallel to form a sheet, and a carbon fiber A sheet was prepared so that the basis weight of the carbon fiber was 190 g / m ² .

  Then, two sheets were introduced into the suspension bath and immersed for 10 seconds, and then the two sheets were overlapped and led out from the suspension as one stacked sheet. The resulting stacked sheet was dried at 150 ° C. for 5 minutes. The amount of resin deposited was 1.4% by mass. Subsequently, the stacked sheets were passed through a roller having a surface temperature of 330 ° C. to melt and impregnate the resin.

The thickness of the surface resin layer of the obtained prepreg, the basis weight, and the resin basis weight of the reinforcing fiber resin layer were as shown in Table 1. The thickness of the prepreg reinforcing fiber resin layer was 115 μm. The prepreg thus obtained was laminated, and autoclaved at 340 ° C. (glass transition temperature of polyetherimide resin + 120 ° C.) and 1000 kPa to obtain a laminate having a laminated structure [+ 45/0 / −45 / 90] _3S. It was. As shown in Table 1, the thickness of the interlayer resin layer of the laminate was as small as 1 μm. The damage area of the carbon fiber reinforced composite material thus obtained was large as shown in Table 1.

[Comparative Example 2]
A prepreg was produced under the same conditions as in Example 1 except that the polyetherimide resin concentration in the suspension was 10.0% by mass and the suspension immersion time of the two carbon fiber A sheets was 30 seconds. The thickness of the surface resin layer of the obtained prepreg was 70 μm. However, this prepreg is a prepreg with a large warp and has a problem in handling.

[Comparative Example 3]
A prepreg was produced under the same conditions as in Example 2 except that two carbon fiber A sheets were laminated in advance and introduced into the suspension as one sheet. The thickness of the surface resin layer of the obtained prepreg was 42 μm. However, this prepreg is a prepreg with a large warp and has a problem in handling.

2 Suspension 4a, 4b Reinforced fiber sheet 6a, 6b Sheet introduction roller 8 Stack sheet take-up roller 10a-10d Guide roller 12, 22 Stack sheet 14 Thermoplastic resin powder 24, 44 suspended in suspension Reinforcing fiber 26, 46 Thermoplastic resin 28a, 28b, 48a, 48b Resin-impregnated fiber layer 30a, 50a Intermediate resin layer 30b, 50b, 64 Surface resin layer 32, 52 Reinforcing fiber resin comprising a resin-impregnated fiber layer and an interlayer resin layer Layer 42 Stacked sheet 62 Stacked sheet 66a, 66b Calendar roller 68 Sheet roll X Arrow indicating the gravity settling direction of the thermoplastic resin powder Y Arrow indicating the traveling direction of the stacked sheet

Claims (4)

A reinforcing fiber resin layer having an intermediate resin layer not containing a reinforcing fiber made of thermoplastic resin between a plurality of resin-impregnated fiber layers in which a sheet made of reinforcing fiber is impregnated with a thermoplastic resin; and A prepreg comprising a surface resin layer not containing reinforcing fibers formed on at least one surface, wherein the prepreg has a basis weight [A] of the thermoplastic resin contained in the reinforcing fiber resin layer and a resin basis weight of the surface resin layer [B ] Is 0.15 <[B] / [A] <0.50
And
A prepreg having a thickness of the surface resin layer of 15 to 30 μm.   The prepreg according to claim 1, wherein the thermoplastic resin is a crystalline or amorphous thermoplastic resin having a melting point or a glass transition temperature of 150 ° C or higher.   The group in which the thermoplastic resin is polypropylene, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, aromatic polyamide, aromatic polyester, aromatic polycarbonate, polyetherimide, polyarylene oxide, thermoplastic polyimide, polyamideimide The prepreg according to claim 1, wherein the prepreg is one or more resins selected from the group consisting of: The manufacturing method of the composite material formed by laminating | stacking and shape | molding the prepreg in any one of Claims 1 thru | or 3.

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